Optimizing Pavement Base, Subbase, and Subgrade Layers for Cost and Performance of Local Roads, Tech Transfer Summary.

摘要

To improve the understanding of the relationship between PCC pavement performance and foundation support conditions, 16 different sites on local city and county roads in Iowa were tested. The sites tested varied in the following aspects: (1) Pavement age, from about 30 days to 42 years; (2) Surface distress conditions, from “poor” to “excellent” (PCI values from 35 to 100); (3) Type of support conditions, from directly supported over natural subgrade to fly ash–stabilized subgrade to 12-in. thick granular subbase materials; (4) Pavement thickness, from 6 in. to 11 in.; and (5) Annual average daily traffic (AADT) from 110 to 8900. At each site, pavement condition, surface deflections under falling weight deflectometer loading, support layer stiffness, and support layer drainage were studied. The field test results were used to calculate in situ parameters used in pavement design per Iowa Statewide Urban Design and Specifications (SUDAS) and AASHTO (1993) design methodologies. The results were documented in a final report and used in the development of a companion set of guidelines.